As an electro-photographic type image forming apparatus, a printer including a photosensitive body and a developing cartridge configured to supply toner to the photosensitive body is known.
A conventional printer is provided with a detection device for detecting information of the developing cartridge assembled therein, for example, for detecting whether or not the assembled developing cartridge is a brand new cartridge.
Japanese Patent Application Publication No. 2006-267994 proposes a laser printer that detects rotation of a detection gear provided in a developing cartridge using an actuator provided in a main casing and that determines information on the developing cartridge based on a detection result.
In the above laser printer, the detection gear has an abutment protrusion corresponding to the information on the developing cartridge. The detection gear is rotated by a predetermined driving amount after assembly of the developing cartridge to the main casing. At this time, the abutment protrusion abuts on the actuator, allowing the rotation of the detection gear to be detected by the actuator.